Conventionally, as a magnet body for a field pole disposed on a rotating electric machine, a magnet body for a field pole formed by providing a plurality of magnet pieces by cleaving a plate-shaped magnet body (hereinafter referred to simply as a “magnet body”) and by bonding a plurality of the magnet pieces to each other is known. Since such magnet body for a field pole is formed of a plurality of the magnet pieces, a volume of each magnet piece can be made small, and an eddy current generated in the magnet piece by fluctuation of a magnetic field by rotation of a rotor can be reduced. As a result, heat generation of the magnet body for a field pole caused by generation of the eddy current can be suppressed, and irreversible heat demagnetization can be prevented (see Patent Literature 1).
JP2009-142081A discloses manufacture of a plurality of magnet pieces by placing a magnet body having a notch provided along a scheduled cleavage line on a die supporting a magnet body on both end portions in a direction perpendicular to the scheduled cleavage line and by pressing an upper part of the scheduled cleavage line downward by a blade so as to cleave the magnet body along the scheduled cleavage line.
The magnet body is fed on the die in a longitudinal direction and cleaved by the blade one by one sequentially from a tip end portion in a feeding direction. The magnet body is cleaved by pressing the blade downward from the upper part of the scheduled cleavage line in a state in which the both sides of the scheduled cleavage line are supported by the die. That is, the magnet body is cleaved by three-point bending.